Ladies – you've often heard it said that your girl friends will probably outlive your husband ... so find good ones.

But there's an increasing body of evidence to support the notion that making good friends might actually be one of the most important decisions you make.

New studies have found that close female friendships can help us live longer, happier, healthier lives, while Oxford University professor Robin Dunbar has said that men need to meet up with their friends at least twice a week and 'do stuff' to be truly healthy.

According to researchers at Flinders University in Australia, women with the highest number of close friends outlive those with the least by 22pc. Whilst other relationships, with a spouse or offspring, were recognised as important, researchers didn't find the same link between those bonds and longevity.

A 2009 Harvard Medical School study found women with close female friends were less likely to develop physical impairments as they aged while other research suggests good friends can help in the battle against stress, cardiovascular problems and even the chances of catching a cold.

The researchers concluded that not having good gal pals was as detrimental to health as smoking or being overweight.

"Women are more likely to confide in their female friends about concerns or health worries," says Pat O'Connor, professor of sociology and social policy at the University of Limerick.

"It's an important outlet where they can talk about what's important to them and as a result that often leads to better mental health."

O'Connor believes female friendships fundamentally cater to a very specific need. She says: "Traditionally men were out and emotionally unavailable so women turned to each other.

Cinema abounds with tales of diehard female friends. This summer saw the portrayal of an unlikely BFF bond between Sandra Bullock and Melissa McCarthy in The Heat while classic gal pal films include Thelma and Louise, Beaches and Steel Magnolias.

But female friendship can be a complex thing and, particularly with relationships forged in the schoolyard, the relationship can sometimes delve into the love/hate zone of 'frenemies'.

Colette McBeth's new book, Precious Thing, traces the path of two childhood friends and their fraught relationship.

The author reckons school friendships are often the most intense relationships making for lasting bonds – and occasionally high drama.

She explains: "Adolescent friendships can be a very toxic environment, full of insecurity, simmering jealousy and constant power play.

"Boys fight and get over it, but girls can be much more subtle and more damaging."

At one point, her lead characters meet after several years apart and Rachel, who was the frumpy one, has lost weight, something Clara takes as a personal affront.

"There is that thing with school friends where we want them to do well, but not so well they eclipse us," McBeth explains.

"It's because we feel like we know them inside out, we know who they are and who they were and established those roles very early on. If someone decides to break out of that it can make us very uncomfortable."

Despite the sinister twists in her thriller, she's at pains to point out it's not a direct reflection of her own friendships.

"There's a scene in the book that is based on how I met one of my closest friends and I don't think she's too happy about it!" she laughs.

"But a lot of people have told me that reading the book made them go back and question their own friendships."

The observation that women share power by sharing information is a crucial difference between male and female friendships. Women build intimacy through face-to-face interaction, sharing confidences with eye contact over a pot of tea or bottle of wine. Men typically interact side by side often bonding through a shared activity like watching a football match.

Psychologist Allison Keating from Dublin's bWell Clinic fears men could be missing out by not indulging in the same therapeutic friendship style as women.

"It doesn't need to be an Oprah style confessional but I think boys and men would benefit hugely to drop old ideals of 'being a man' and connecting in a way that allows for them to voice worries, concerns and fears," she explains.

"If boys were taught at school that it was okay to show your authentic self, it might finally put to an end the level of shame and fear that plagues the state of mental health."